Automatic clutch system for motor vehicles



C. L. HOPKINS Filed Sept. l, 1932 4 Sheets-Sheet l Sept. 22, 1936.

AUTOMATIC CLUTCH sYsTEM FOR MOTOR VEHICLES Sept. 22, 1936. C, L, HOPK|N3 V2,055,255

AUTOMATIC CLUTCH SYSTEM FOR MOTOR VEHICLES Filed Sept. l, 1952 4 Sheets-Sheet 2 INVENTOR.

A TTORNEYS.

AUTOMATIC CLUTCH SYSTEM FOR MOTOR VEHICLES 1932 4 Sheets-Sheet 3 Filed Sept. l

/IFZ

NVENTOR ATTORNEYS .llrmzfll /23 /z l lll-ll l E I I i l I l I I l l l I Sept. 22, 1936. c, HOPKINS AUTOMATICl CLUTCH SYSTEM FOR MOTOR VEHICLES Filed Sept. l

4 Sheets-Sheet 4 INVENTOR.

9m W ATTORNEYS.

'Patented Sept. 22, 1936 i, UNITED STATES PATENT CFI-ICE v 2,055,255 l AUTOMATIC CLUTCH sYsTEM Foa MoTon VEHICLES Charles L. `Hopkins,

River Forest, Ill., assignor to Bendix Products Corporation, South Bend, Ind., a corporation of Indiana Application September 1, 1932, Serial No. 631,314

7 Claims.

' scending hills. In the present system the braking power of the engine is always available without the necessity of moving or manipulating the free-wheeling button or any locking-out device, whether in free-wheeling or conventional condition.

Another object is to provide an automatic clutch system which permits the shifting of gears from a, higher to a lower gear, or from a lower to a higher gear, at any car speed, without clashing of gears, even though the gear-shift mechanism be of the simplest type, thus eliminating the need of an expensive so-called synchro-mesh transmission.

Still another object is to lessen the wear on the i clutch iacings `as compared with known systems in which the clutch opens and Closes with the release or depression of theaccelerator.

Other advantages and objects of the invention will appear from a study of the following specication.

There has recently come into extensive use what is known as the automatic clutch, in which the partial vacuum created in the intake manifold furnish power for of the engine is utilized to operating the friction' clutch. In some cases a free-wheeling effect is obtained by controlling the operation of valves of the automatic clutch mech@ anism from the accelerator, so that the clutch opens when the accelerator is released and closes when it is depressed. In other cases the freewheeling eiect is obtained by the use of an overrunning clutch behind the transmission. The automatic friction clutch and the overrunning clutch are sometimes employed in the same power installation.

In the form of my invention shown in the drawings I have provided the usual friction clutch immediately behind the engine. This will be called the main clutch. This clutch is followed by the gear-shift mechanism or transmission unit, and this in turn by a positive clutch having parts which interlock when the clutch is closed. Means are provided (a cylinder and suction operated piston being shown) for openingand closing these clutches. These parts are so combined with other elements that when the accelerator is released position. The engine (Cl. 15m-.01)

both the main clutch and the rear clutch open quickly, leaving the transmission disconnected at both ends; that is, from the engine in front of it and the propeller shaft behind it.- If the car is moving it may nowcoast or free wheel. The freeing of the transmission permits the selection of the desired gear combination without clashing,

the shifting lever being moved to any position without the exercise -of skill on the part of the driver. This opening of the clutches occurs during the last part of the movement of the accelerator, after the throttle has closed to the idling is able to hold back the car at all speeds, and acts as a brake except when the accelerator is fully released, and this will be the case only when it is desired to coast. This is true `even when the free-wheeling button is in.

When the accelerator is depressed the iirst part of its movement is accompanied by the quick closing of the main clutch, when further movement of the accelerator opens the throttle of the engine.

When the engine has attained the proper speed,

that is, such a speed that the parts of the rear clutch are turning together at approximately the same speed, the rear clutch suddenly closes. It will be observed that there is an interval of time between the closing of the main clutch and the closing of the rear clutch. This is, of course, necessary so as to give the engine time to come up to the speed necessary for synchronization. It will be seen that as the main clutch closes there is no slipping of the discs on each other, as there is nothing to be brought up to the speed of the engine except the gears in the transmission and, moreover, the engine is turning only at idling speed at that time.

In the accompanying drawings, in which I have shown an embodiment of my invention:

Figure l is vation the variable speed transmission or gear box and some other parts of an automobile, with the elements of the improved clutch system;

Fig. 1a. is an elevational view showing the throttle lever ofthe 'carburetor and the lost motion connection between Fig. 2 is a top plan view of the rear clutch box, the cover of the box being removed to expose the clutch and other parts enclosed in this box;

this lever and the forwardl end of the accelerator rod;

a general view, showing in side ele- 5 of Fig. 2, certain parts being shown in ferent positions in these three views;

In the sectional views of Figs. 3 to 7, inclusive,

dif-

parts are in some cases broken away or omitted sake of clearness;

Fig. 16 showsa detail of the device which prevents the closing of the rear clutch until the parts of the latter rotate at about the same speed;

being shown in their normal or non-coasting positions, as when the car is standing or when the accelerator is depressed and the engine is turning the drive wheels;

Fig. 18 shows the same parts as Fig. 17, but inA this case the car is coasting;

a section on opening and closing of the and Fig. 20 showsan arrangement of button and valve control slightly different from that of Fig. 1.

In the several figures of the drawings, I0 is the selective speed transmission unit or gear box, and II is the gear shift lever. The accelerator pedal is designated I2. Secured to the rock shaft I3 of the main clutch is the clutch lever I4, one arm I4a of whichis engaged by a lug I5 on the clutch pedal I6 when the latter is depressed. This pedal turns loosely on the shaft I3 and is normally held in its non-depressed position by a spring I1. Also carried by the shaft I3 is a member I8 which is arranged to rock or swing on the shaft. 'I'his member is formed with a lug or projection I9 for engagement with the arm 20 o1' the lever I4. A pull rod 2| is connected at communication valve;

one end to the swinging member I8, the other piston is open to the atmosphere.

At the rear end of the gear box I0 is a casing 25 which forms a other parts, as explained hereinafter. Secured to the side of this housing is a cylindrical valve the cylinder is cut oil', while in Fig. 9 communicahousing for a small clutch and arm 60,

a supporting plate 42 side of the gear box IIJ. the movement of the which is secured to the Stop pins 43 and 44 limit swinging members. A

y spring 45 tends to move the valve 21 to the open point will open the throttle. Now. as long as button 46 remains undepressed, as shown in Fig. 1,

, the accelerator pedal spring will move valve 21 to its open position,`

with pin 36 at the right-hand end of slot 31 in member 39. If the accelerator pedal be now depressed, spring 6I will cause member 39 to move to the right, and the valve will be moved out (to the left) to the closed position. Furthervmovement of the accelerator pedal will open the throttle and increase the speed of the engine. When the foot is removed from the accelerator. spring 62 closes the throttle.

The clutch pedal I6, as already'explained. is held in its normal position by spring I1. When the pedal is depressed the projection or lug I5 on the pedal engages the rm I4a,of the clutch lever I4 which is securedon the rock shaft I3 of the clutch. The details of the clutch itself are not shown, as there is nothing unusual in its construction. This clutch has the usual springs for normally holding the discs or disc shaft, the turning .of which in the proper direction causes the clutch to open or disengage, The first part of the movement of the clutch pedal brings the lug Vl5 against the arm I4a of. the lever, then further movement of the pedal opens the clutch.

As long as button shown, the clutch must be disengaged manually by the driver in the usual manner. Assume, however, that the button be depressed, the accelerator pedal remaining as shown. The valve 21, which will be called the ,communication valve, is opened by the spring 45 and the suction effect due to the lowered pressure in the intake manifold of the running engine causes a partial vacuum to exist in the cylinder, resulting in the piston 22 being drawn in and lever I8 being swung to theright. Lug I9 on this lever does not engage the arm 26 on the clutch lever until the piston has moved in a certain distance. Then the clutch opens and then a further movement of the piston occurs after the clutch has disengaged. The reasons for providing slack or lost motion between the piston and the clutch at each end of the piston stroke will be explained below.

As long as the button is held down 'and the accelerator pedal is not depressed, the piston will hold the clutch open. If now the button be released, the pin 36 will be moved to the position shown in Fig. 1 and communication valve 21 will be closed. Or if the button be still depressed and I2 be depressed the same effect will be had; then further movement of. the accelerator will increase the speed of the engine. With communication between engine and cylinder cut off bythe closing of valve 21 the clutch will not be permitted to close, however, unless air is admitted to the cylinder behind the piston. The purpose of valve 28, which will be called the ,venting. valve, is to control the admission of air to the cylinder after valve 21 has been closed. When the piston has returned sufciently to permit the clutch to fully close, the lug I9 leaves the end 26 of the clutch lever and a spring 63 moves the piston and the lever I8 the rest of the way back.

Within the housing 25 is a positive clutch comprlsing two members having interengaging teeth. This might be termed the rear clutch. One of its members, designated 64, is splined to the rear end of the shaft 65 which extends from the gear box and thus turns with itand has movement lengthwise of the shaft. The other member. 66 is sefacings in engagement and includes in its construction a rock 46 remains in the position" l the positions shown in Fig.

' pressed or not.

cured to a short shaft 61 which extends rearwardly to the universal joint (not shown). The slidingmember 64 of this rear clutch is moved by a yoke 68, carried by a slide rod 69supported atits ends in apertures in bosses 10 and 1I cast in the housing 25.

`The slide rod 69 is moved back and forth by an arm 12 which extends downwardly from a rock shaft 13 and engages collars 14 and 15 on the slide rod 69. This rock shaft 13 is journalled at one end in the housing 25, the other end be- Y ing supported by and turning yin the elongated hub 16a of a lever 16, this hub passing through the wall of the housing 25 and extending into the space therein. An arm 11 is secured to the projecting end of. shaft 13. Lever 16 is connected by a rod 18 to lever I6 so as to be swung through an arc when the piston moves in the cylinder 23. The arm`11 has a lug 19 projecting into the path of a lug 66 on the lever 16.

With the parts in the positions shown in Fig. 1 the positive rear clutch is held closed, as seen for instance in Fig. 5, by the spring 63. To open and close this clutch, arm 11 must be swung through the arc included between the lines marked CI and C2. When the piston is drawn into the cylinder the main clutch is fully .opened before the rear clutch starts to open. As explained above, the rst part of the movement of the piston is used 4up in bringing the lug I9 of lever I8 into contact with the arm 2U of the clutch lever I4. Further movement of the piston opens the main clutch; then a projection 8l on lever 16 engages lug 19 on the rear clutch arm 11 and opens the rear clutch. Lever 16 13. It is to be understood that the whole movement of the piston and other parts takes place very quickly.

It will be seen that pressure of the parts of therear clutch upon each other is removed be- 'fore this clutch is opened, because of the fact that the engine has been cut off by the opening of the main clutch. 4Assuming that the button 46 is held down by th\e foot of the driver and the car is being moved along the road by power from the engine. Now, if the accelerator Vpedal is suddenly released, the engine will drop to idling speed while at the same time the main clutch will open to release the engine, this being immediately followed by the opening ofthe rear clutch, and the car is permitted to coast. Or suppose that instead of coasting, reduce the speed of the car by partly closing the throttle by means of the accelerator. With a free-wheeling system which includes an overrunning clutch in'the power transmission line this cannot be done when in free wheeling, but itis necessary for the driver to shift his foot from the accelerator to the brake pedal when he desires to reduce the speed of the car. In the present system the car speed may be decreased as well as increased by varying the pressure on the accelerator, unless the accelerator is completely released. In descending hills the braking power of the engine may be used, whether the button be de- This will be discussed further following an explanation of the means provided for insuring the closing of the clutches at the proper times and in the proper order.

It will be understood that after the main clutch and the rearclutch have both opened, as when coasting, the interlocking members of the rear clutch will rotate at different speeds. The selective transmission unit is cut off from the engine ahead of it and from and arm 11 are now in the driver desires to the drive wheels of the car,

and, of course, the gears will stop turning. The lightly gripped between the two anges and thus rear member 66 of the rear clutch turns with the tends to turn with these flanges whenever spur propel1er.shaft,while the other clutch member 64 gear 94 revolves around shaft 84. A at barstops when the gears stop. For this reason it is like latch member |02, formed with a slot |03 to necessary that when the clutches close the main accommodate shaft 84, is formed with a tongue 5 the interlocking members of the rear clutch may latch member fits' when the latch member is in its 10 be brought together without clashing. Means normal, raised position.

are provided, therefore, whereby the rear clutch The upper end of latch member |02 is pivotis prevented from* closing unless or until the enally secured to the o'uter end of an arm |06 which of the rear clutch are revolving at substantially rock shaft extends outside casing 25 and carries 15 lthe engine, the main clutch is opened rst, folvalve in when permitted to do so.

lowed immediately by the opening of the second By referring to Figs. 8 to 12, inclusive, it will 20 clutch, the engine meantime slowing down to be seen that venting valve 28 is open at both idling speed. When the piston moves in the other ends of the movement of the plunger, and that direction the lever '|6 moves ,to the position shown it is closed at a` ertain position between these in Fig. 14, the main clutch meantime closing. extremes. The miter gears and other parts as- Then the piston is arrested until the engine speed sociated with shaft 84 together form a device 25 lfrom completing its stroke until the proper time, substantially the same speed. 30

will now be described. Referring particularly to Figs. 2, 3, and 15, it Shaft 65 carries a spur gear 82 fast on the shaft will be seen that a ve-pointed star wheel ||0 to turn t ereon. Shaft 84 is AJournalled at its cams and is free to turn on the hub of lever 16. 35

gear 88 0n Shaft 67. Gears 82, 83, 85 and 88 have turn with the lever. An arm ||5 is carried by 40 the small gear 86interposed between gears 85 and g hub of arm ||5 carries also a short arm ||9 45 88,gear 85 andthe shaft to which it is secured which engages a projecting lug |20 on an arm normally turn in the opposite direction from loose |2| on the hub |06 of arm |06. gear 83. f Fast on shaft 131s the hub |22 of an arm |23. On the same hub with gear 83 is a miter gear 89, Between this hub |22 and hub 4 is a. cam plate which together with gear 83 turns loosely on shaft |24, turning loosely on the shaft. This cam plate 50 84. Facing miter gear 89 is another miter gear has an arm |25 extending radially from it into 90, fast on shaft 84. A sleeve 9|, loosely turning the path of a pin |26 on arm |23', and also into posite directions and at like speed when the rear tends to turn the cam plate clockwise. 'Ihis in opposite directions and at the same speed, gear device hereinabove described, controls the re- 60 94 will be carried around shaft 84. Bracket 92 turn of the venting valve after it has been moved and sleeve 9| will turn on the shaft and permit out.

gear 94 to remain in proper mesh with both of Referring now to Fig. 8, which shows the valve the other miter gears. When gears 89 and 90 plungers in their normal positions, or the posirevolve in opposite directions and at different tions which they occupy when the accelerator |2 65 speeds sleeve 9| will turn at a speed equal to oneand button 46 are not'depressed (see Fig. 1), it half the dierence between the speeds of these will be observed that the valve casing 26 has two two gears, and in the same direction as the faster vent ports |28 and |29, as Well as the other ports moving gear. leading to the engine manifold and vacuum Secured to sleeve 9| at its end opposite the miter cylinder, respectively. Plunger 21, when in the 70 a flat disc-like member 99 having two downwardly duit are in communication with the atmosphere projecting tongues |00 and |0|. This member is through a passage |30 formed in valve plunger 75 fifi 28 and ports |3| and |32 in the plunger, as'these ports are in register with vent ports |28 and |29.

As already explained, if the accelerator be released while button 46 is depressed, the piston ,22 in the vacuum cylinder will be drawn back. The first part of the movement of member i8 will close the space between lug |9 and arm 20 of the main clutch lever. Further movement of the piston opens the main clutch, then still further movement permits projection 8| on lever 16 to engage lug 19 on rear clutch arm 11 and open the rear clutch. During this movement of the piston and the lever 16 the star wheel ||0 and pin |21 turn clockwise. The star wheel swings arm back and turns rock shaft |01 in the direction to move valve 28 to the position shown in Fig. 9. This figure shows the positions of the valves when the clutches are held open by the piston for coasting or gear shifting. Fig. 13 shows the positions of lever 16, rear clutch arm 11, valve-operating arm |08, and the valve, while Fig. 18 shows some of the other parts which are located within the casing.

It will be seen that the star wheel, which has turnedgthrough one-fifth of a revolution, has permitted the roller cam follower ||1 to drop back to its original, normal.A position, thus acting as a detent to hold the starpwheel against turningvbackward. The venting valve, however, is for the present held against the tendency of spring |09 to return it by the engagement of arm |2| with cam plate |24. When the star wheel turned forward, that is, clockwise, arm ||9 on the same hub as arm ||5, which carries the roller, engaged lug |20 on arm |2|thus turning rock shaft |01. At the same time, cam plate |24 was permitted to move clockwise a certain distance, but was prevented from following pin |21 beyond the point where arm |23 stopped. This arm has, of course, only the same amount of angular movement as the rear clutch arm 11, and moves with it, while pin |21 has Athe same amount of angular movement as lever 13 and moves with it.

If now the button be released or the acceleratordepressed, communication valve 21 will return to normal position, but venting valve 28 will at first be held in its present position by the cam plate. Fig. shows the valves at this time, and it will be noted that the suction is cut off and cylinder 23 vented. This permits the piston to be drawn out by spring 63 until pin |21 engages the arm on the cam plate and moves the latter slightly. The cam plate is formed with a quick drop and a shoulder at'l33. Foot |2|a on lever |2| drops upon this shoulder and the valve is held at the position shown in Fig. 1l, the vent ports being nearly closed. The engagement of pin |21 with the arm on the cam plate occurs before lug 30 on lever 16 reaches the lug on clutch arm 11, and while the main clutch is closing, but just before this clutch has completely closed. The clutch plates move toward each other very quickly at first, but do not come together with a shock because of the restricted venting during the last part of the movement. There is noVY destructive slippage of the clutch plates even with this rapid closing of the clutch, because the rear clutch is open and only the gears in the transmission have to be started or speeded up.

Due to the fact that the rear clutch'is open, there is relative movement between the parts 64 and 66 of this clutch, and consequently sleeve 9|, iiange 96 and flange 91 are slowly turning in one direction or the other, depending on which foot |2|a on the arm |2| passes 0H the cam n plate, the valve is permitted to move only a short distance farther in, because tongue |04 on the.

latch bar engages one of the shoulders |34 or |35 on the plate 99, as seen in Fig. 16. The venting valve is thus arrested at the position shown in Fig. l2 with the vent ports. closed. This prevents the piston in the vacuum cylinder from moving any farther for the present, and, of course, the rear clutch does not close.

It will be remembered that when the accelerator is depressed it` moves a certain distance before the-throttle is affected. With the button down, pressure on the accelerator causes the main clutch to close quickly, usually before the throttle has started to open, or, at most, before the engine has increased its speed greatly. Sup.. pose the car were' coasting. The rear member Vt6 of the clutch would be turning while the front 'the speed of member 64 would still be less than that of member 66; therefore the engine should have its speed increased until these members were turning at something like the same speed. It will be seen that as long as the plate 99 is urged to turn, the tongue |04 on the latch bal' will remain caught on the shoulder |34, as seen in Fig. 16. (If the engine were turning too fast the latch would catch on shoulder |35.) As member 64 is now turning with the engine, whose speed is increasing, the members will very soon turn at the same speed. The `instant that member 64 turns faster than member 66, plate 99 will start to turn the other way. This causes the tongue to slip oi into the notch |05, causing arm |06 to y up and valve arm |09 to swing to the left, carrying venting valve 28 to the position shown in Fig. 8. The venting valve being now open. the piston is` drawn out to the end of its stroke by spring 63, the projection 80 on 19 on arm 11 and closing the rear clutch.

It will be seen that the above explanation of the action of the synchronizing means is true when the gear shift is in second or first gear, as well as when it is in high, even though the engine runs faster relatively to the speed of the drive wheels of the car, and that in shifting from one gear ratio to another the same action takes place. The mechanism described above does not, however, provide for starting a standing car.

When starting the car, either in low or in reverse, it is necessary that the rearY clutch close first and that the main clutch close slowly so as to permit some slipping of the clutch until the car gets under way. To accomplish this a lever is pivoted on shaft 13, one arm |36 of which extends downwardly and has a lug |31 which may engage the arm 12. A spring |38, coiled around shaft 13, tends to turn the lever on the shaft and holds the lug |31 against arml 12. 'Ihe other arm |39 of the lever carries a roller |40. When the gear shift on the car is put into either low the shoulder and go up' lever 16 engaging lug` stores energy in spring |38, tending to turn l 'This rod, designated `|4|,

or reverse, the right-hand slide rod in the transmission is slid either forwardly or` toward the rear. 'I'his rod is made longer than usual so that it extends back into the casing of the rear clutch. has secured to its vrear end a cam plate |42, so formed that when the rod is in an intermediate position the movement of lever arm |39 will not be interfered with. This position of the rod corresponds to neutral, second and high. When the rod has moved endwise, as when in low or reverse, the cam engages roller |48 and depresses arm |39, as seen in Fig. 7. This carries lug |31 away from arm 12, and shaft 13 and close the rear clutch.

4When starting the car with the button depressed, the accelerator is, of course, released and the piston is drawn in, opening both-clutches. When the gear shift lever is put in low or reverse, as desired, cam plate |42 presses down lever arm |39 and spring |38 tends to close the rear clutch. This is at first prevented by the engagement of projection 8| on lever 16 with the lug on arm 11. Then as the accelerator is depressed, the piston starts to run 4out and spring |38 causes arm 'Il to follow the projection-88 back, closing the rear clutch. This Varrangement of plate cam, lever and spring thus causes the rear clutch to close during the rst part of the movement of the piston when in low or reverse.

Now it will be observed thatin'this case pin |26, which moves with the clutch arm 11, turns the cam plate |24 counterclockwise earlier than pin 21 would have done it. Valve 28 is thus permitted to move at once to the position shown in Fig..l1, 'where the vent ports are nearly closed. This partial venting permits the piston to be drawn slowly out of the cylinder by spring 63 and the clutch springs, land the clutch closes slowly, the plates slipping on each other until the car gets under way. After the clutch has closed the piston and lever 16 continue to move and pin |21 engages arm |25 on cam plate |24, returning the cam plate to its normal position, as seen in Fig. 17. This permits the venting valve to go to the position shown in Fig. 8, where the vent ports are open, unless latch bar |02 is held by one of the shoulders |34, |35, in which case the valve would be permitted to move only to the position seen in Fig. 12. This is immaterial, as both clutches have already closed.

As explained hereinabove, when the accelerator is depressed after the clutches have been opened for coasting or shifting from one gear ratio to another, the closing movements of these clutches arecontrolled by valve 28 which regulates the admission of air; to the cylinder 23 behind the piston 22. Atmospheric pressure on the front of the piston opposes spring 63 and the springs of the main clutch and prevents them from closing the clutches until this pressure is balanced by atmospheric pressure behind the piston. This would be true whether the piston had been moved back by suction from the engine intake or by power derived from some other source.

The button which, when moved in, aiects the change from the free-wheeling condition to the conventional condition may, if desired, be located on the instrument panel instead of at the floor, as seen in Fig. 1. In this case button 46, lever 46a and rod 41 are replaced by a push-pull wire |43 sliding in a tube |44, as shown in Fig. 20. At the upper end of this wire is a button |45 supported by the panel |46 and arranged to be drawn out or pushed in. When the button is out the slotted member 40 is held in its left-hand position, as shown, and movement of the accelerator does not aifect valve 21. When the button is in, member 48 is held in its yright-hand position and valve 21 is permitted to move in when the accelerator is released and to be drawn out when the accelerator is depressed.

- Further modifications will be apparent to those skilled in the art and it is desired, therefore, that the invention be limited only by the prior art and the scope of the appended claims.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

l. In a motor vehicle having an engine, a variable speed transmission, a clutch between them and an accelerator for the engine, a second clutch behind said transmission, and automatic means for opening and closing said clutches arranged to open both clutches substantially at the same time, said means being further arranged to close one of said clutches when the accelerator is moved to increase the speed of the engine and to close the other clutch only when the speed of the engine has increased to the point where the parts of said other clutch turn at substantially the same speed.

. In a motor vehicle having an engine, a variable speed transmission and a friction clutch on one side of said transmission, a positive clutch on the other side of said transmission, power operated manually controlled means for opening and closing said clutches, and means whereby the gear reduction ratio selected in the transmission determines which clutch shall close first.

3. In a motor vehicle having an engine and a variable speed transmission, a clutch between the engine and the transmission, a second clutch behind the transmission, manually controlled means for opening said clutches, and power-operated automatic means arranged to close the firstnamed clutch when the engine speed is increased from idling speed and to thereafter close the second clutch when the parts of said second clutch turn at substantially equal speed.

4. In a motor vehicle having an engine and a variable speed transmission, the combination of two clutches, one on each side of said transmission, and means for opening and closing said clutches arranged to open both clutches substantially simultaneously and including fluid pressure means for controlling the closing of said clutches, and means for controlling said fluid pressure means comprising a valve and operating means therefor, said operating means comprising parts driven at speeds proportional to the speeds of the interengaging parts of one of the clutches and arrangedto so control said valve as to cause said one clutch to close only when its interengaging parts turn at substantially equal speeds.

5. In a motor vehicle having an engine anda variable speed transmission, a clutch between the engine and the transmission, a second clutch behind the transmission, and means for opening and closing said clutches including spring means tending to close said clutches, means arranged to oppose and control said spring means, and means for controlling said spring-opposing means, said last-named means comprising parts driven at speeds proportional to the engaging parts of one of the clutches and arranged to so control said spring opposing means as to cause said one clutch to close only when its said parts turn at substantially equal speeds.

6. In a motor vehicle having an engine and a variable speed transmission, the combination of two clutches, one ahead of and the other behind the transmission, and means for opening and closing said clutches arranged to open both of said clutches substantially simultaneously and including uid pressure means for controlling the closing of said clutches comprising a movable piston arranged to cause one of said clutches to close during a part of the movement of said piston and the other clutch to close during further movement of the piston in the same direction, automatic means arranged to delay the further movement of the piston after said one clutch has closed until the interengagng parts of said other clutch have substantially no relative movement.

7. In a motor vehicle having an engine and a variable speed transmission, the combination of a clutch between the engine and the transmission, a second clutch behind said transmission, and

and l i controlling the valve means comprising elements driven at speeds proportional to the interengaging parts of the second clutch'and arranged to delay further movement of the piston after the firstnamed clutch has closed until the interengaging parts of the second clutch revolve at substantially the same speed.

CHARLES L. HOPKINS. 

